Qargha

The Great Blue Hole is a large underwater sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll {convert|70|km|0|mi|lk=off} from the mainland and Belize City. The hole is circular in shape, over {convert|300|m|0|yd|lk=off} across and {convert|124|m|0|yd} deep. It was formed during several episodes of Quaternar...
Found on http://en.wikipedia.org/wiki/Qargha
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